Hitherto, as a main body of a flush toilet of a western type, there is generally known a flush toilet having the configuration such that a bowl section 100 is provided with a water supply and discharge system assembly 200 at its back portion, as shown in FIGS. 27(a) and 28(a).
As shown in FIGS. 27(a) and 28(a), the bowl section 100 comprises a waste receipt surface section 110, a water chamber surface section 111 located underneath the water level of a water chamber section 120, and a dry surface section 112 formed continuously with the water chamber surface section 111 and located above the water level of the water chamber section 111.
At the periphery of an upper opening of the bowl section 100 is provided a rim port-ion 130 having a predetermined width. The rim portion 130 comprises an inner peripheral wall 131, a rim rinse waterway 140, a water supply outlet 210 communicating with a water supply source not shown in the figures, a water supply conduit 220 communicating the water supply outlet 210 with the rim rinse waterway 140, and a drain path 150 communicating with a drain outlet 300.
A description will be made of the configuration of a flush water passage of the main body of the flush toilet which is known to the art.
As shown in FIG. 27(a), a flush toilet X1 is configured such that a number of water discharge holes 160 directed toward the waste receipt surface section 110 are disposed at a lower side surface portion of the rim rinse waterway 140. The flush water discharged from the water supply outlet 210 was passed through the water supply passage 220 to the rim rinse waterway 140. The water is then supplied from the water discharge holes 160 toward the waste receipt surface section 110 to wash the waste receipt surface section 110 away and discharged through the drain path 150 from the drain outlet 300, as shown in FIG. 27(b).
On the other hand, as shown in FIG. 28(a), a flush toilet X2 is configured such that a portion of a rim rinse waterway 140 is divided into two branch waterways to form a flush water jet passage 400. In addition to the flush water stream as described above, the flush water passes through the flush jet passage 400 from the rim rinse waterway 140 and is then discharged through a flush water jet discharge hole 410 into the drain path 150, as shown in FIG. 28(a). It is to be noted herein that a slit-shaped water discharge outlet 170 extending continuously over the entire periphery can be disposed on a lower side surface of a rim portion 130, as shown in FIG. 30, in place of the water discharge holes 160 formed in a large number on the lower side surface section of the rim portion 140 (as shown in FIG. 29).
Moreover, the main body of a flush toilet is generally made from porcelain that has a rough surface so that water can be absorbed therein although the amount of the water absorbed is very slight. Therefore, the porcelain body is surface finished by coating the surface thereof with a vitreous glaze in order to lose its water absorption property. This can ensure a high level of sanitation.
The flush toilets X1 and X2, however, have the following problems which have been left unsolved yet. Each of the flush toilets X1 and X2, each having the configuration of a flush water passage as described above, has a lower side surface section of the rim portion 130 structured in a complex configuration such that the rim portion 130 is protruding downwardly inside the bowl section 100 because flush water is caused to flow toward the waste receipt surface section 110. Therefore, it is difficult to coat the lower side surface section of the rim portion 130 and other sections with the glaze so that they are likely to be contaminated with germs or attached with waste product. Moreover, it is further difficult to clean the such sections because they are formed with depression that cannot be looked easily as a dead angle from the vision of the user. Therefore, it is difficult to ensure a high level of sanitation. In addition, the germs or waste product attached thereto cause a source of generating malodor.
Furthermore, the rim rinse waterway 140 has to be provided with a large number of the water discharge holes 160 or slit-shaped water discharge outlets 170 on the lower side surface section thereof in the manner as described above. Therefore, the steps for manufacturing the such flush toilets become complicated leading to a rise in costs of manufacturing the flush toilets.